5.2. Securing the boot menu with password by using the bootloader RHEL system role

Procedure

1. Store your sensitive variables in an encrypted file:

   1. Create the vault:

      $ ansible-vault create ~/vault.yml
      New Vault password: <vault_password>
      Confirm New Vault password: <vault_password>

   2. After the ansible-vault create command opens an editor, enter the sensitive data in the <key>: <value> format:

      pwd: <password>

   3. Save the changes, and close the editor. Ansible encrypts the data in the vault.

2. Create a playbook file, for example, ~/playbook.yml, with the following content:

   ---
   - name: Configuration and management of GRUB2 boot loader
     hosts: managed-node-01.example.com
     vars_files:
       - ~/vault.yml
     tasks:
       - name: Set the bootloader password
         ansible.builtin.include_role:
           name: redhat.rhel_system_roles.bootloader
         vars:
           bootloader_password: "{{ pwd }}"
           bootloader_reboot_ok: true

   The settings specified in the example playbook include the following:

   bootloader_password: "{{ pwd }}"

   The variable ensures protection of boot parameters with a password.

   bootloader_reboot_ok: true

   The role detects that a reboot is needed for the changes to take effect and performs a restart of the managed node.

   重要

   Changing the boot loader password is not an idempotent transaction. This means that if you apply the same Ansible playbook again, the result will not be the same, and the state of the managed node will change.

   For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-system-roles.bootloader/README.md file on the control node.

3. Validate the playbook syntax:

   $ ansible-playbook --syntax-check --ask-vault-pass ~/playbook.yml

   Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

4. Run the playbook:

   $ ansible-playbook --ask-vault-pass ~/playbook.yml

Verification

1. On your managed node during the GRUB2 boot menu screen, press the e key for edit.

   

2. You will be prompted for a username and a password:

   

   Enter username: root

   The boot loader username is always root and you do not need to specify it in your Ansible playbook.

   Enter password: <password>

   The boot loader password corresponds to the pwd variable that you defined in the vault.yml file.

3. You can view or edit configuration of the particular boot loader entry: